Experts had struggled to predict exactly where the lab would make its re-entry – and China’s space agency wrongly suggested it would be off Sao Paulo, Brazil, shortly before the moment came.

The European Space Agency said in advance that Tiangong-1 would probably break up over water, which covers much of the Earth’s surface.

It stressed that the chances of anyone being hit by debris from the module were “10 million times smaller than the yearly chance of being hit by lightning”.

It’s not clear how much of the debris reached the Earth’s surface intact.

Why did the space lab fall like this?

Ideally, the 10m (32ft)-long Tiangong module would have been taken out of orbit in a planned manner.

Traditionally, thrusters are fired on large vehicles to drive them towards a remote zone over the Southern Ocean. This option appears not to have been available after the loss of command links.

Thirteen space agencies, under the leadership of the European Space Agency, used radar and optical observations to follow Tiangong’s path around the globe.

Tiangong was certainly on the large size for uncontrolled re-entry objects, but it was far from being the biggest, historically:

The US space agency’s Skylab was almost 80 tonnes in mass when it came back partially uncontrolled in 1979. Parts struck Western Australia but no-one on the ground was injuredNasa’s Columbia shuttle would also have to be classed as an uncontrolled re-entry. Its mass was more than 100 tonnes when it made its tragic return from orbit in 2003. Again, no-one on the ground was hit as debris scattered through the US states of Texas and LouisianaAstrophysicist Jonathan McDowell believes Tiangong is only the 50th most massive object to come back uncontrolled.

Jonathan McDowell

✔@planet4589

By my calculations, Tiangong-1 will be the 50th most massive uncontrolled reentry from Earth orbit in history.